Large-scale Recording of Neurons by Movable Silicon Probes in Behaving Rodents

Summary

We describe methods for large-scale recording of multiple single units and local field potential in behaving rodents with silicon probes. Drive fabrication, probe attachment to the drive and probe implantation processes are illustrated in sufficient details for easy replication.

Abstract

A major challenge in neuroscience is linking behavior to the collective activity of neural assemblies. Understanding of input-output relationships of neurons and circuits requires methods with the spatial selectivity and temporal resolution appropriate for mechanistic analysis of neural ensembles in the behaving animal, i.e. recording of representatively large samples of isolated single neurons. Ensemble monitoring of neuronal activity has progressed remarkably in the past decade in both small and large-brained animals, including human subjects^1-11. Multiple-site recording with silicon-based devices are particularly effective because of their scalability, small volume and geometric design.

Here, we describe methods for recording multiple single neurons and local field potential in behaving rodents, using commercially available micro-machined silicon probes with custom-made accessory components. There are two basic options for interfacing silicon probes to preamplifiers: printed circuit boards and flexible cables. Probe supplying companies (http://www.neuronexustech.com/; http://www.sbmicrosystems.com/; http://www.acreo.se/) usually provide the bonding service and deliver probes bonded to printed circuit boards or flexible cables. Here, we describe the implantation of a 4-shank, 32-site probe attached to flexible polyimide cable, and mounted on a movable microdrive. Each step of the probe preparation, microdrive construction and surgery is illustrated so that the end user can easily replicate the process.

Protocol

1. Construction of the microdrive

All drives are made from the same basic elements: a moving part, which carries the electrode and a fixed part, which is anchored to the skull. An ideal microdrive allows smooth but long enough travel of the electrode in multiple small steps, is sturdy enough to prevent accidental movement of the electrode, easy to manipulate by the experimenter without interfering with the animal's behavior, small in size and light in weight. As a result of these competing requirements, different drives suite different applications.

Only 4 parts are needed to build our basic drive: a brass flat hea....

Discussion

This movie illustrates the implantation procedure of silicon probes for chronic large-scale recordings in the behaving rat. Critical steps to ensure quality recordings of neuronal activity arise from the fragility of both biological (brain tissue) and technical (silicon probe) materials. Special care should be taken while handling the probe to avoid any contact of shanks with any remotely "hard" surface (for example, the shanks would break if one tried to implant them in the brain without removing the dura). Similarly, a.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Silicon probe Buzsaki32, 4 shanks x 8 sites. Packaging: flexible polyamide cable	Material	NeuroNexus Technologies	Probe: buzsaki32 Packaging: HC32	Recording probe
Round Brass Screw, 00-90 x 1/2 Round Brass Screws	Material	JIMorris	R0090B500	Drive part
Brass Hex Nut, 00-90	Material	JIMorris	N0090B	Drive part
Brass C260 Strip, ASTM-B36 Thickness: 0.025", Length: 12", Width: 1/2"	Material	Small Parts, Inc.	B000FMYU72	Drive part
Connector Header, pitch 2mm, male, single row, straigt, 36 positions	Material	Digi-Key	2163S-36-ND	Drive part
2-part Sylgard silicon Elastomer	Material	World Precision Instruments, Inc.	SYLG184	To extra-insulate the probe
Decon Contrad 70 Liquid Detergent	Reagent	Fisher Scientific	04-355 Decon Laboratories No.:1002	To clean the recording sites
Impedance Conditioning Module	Equipment	FHC, Inc.	55-70-0	Impedance meter
niPOD - 32 channels	Equipment	NeuroNexus Technologies	niPOD -32	Impedance meter
Grip Cement Industrial Grade	Material	Caulk Dentsply	675571 (powder) 675572 (solvent)	Grip cement
1,1’-dioctadecyl-3,3,3’,3’-tetramethylindocarbocyanine perchlorate (’DiI’; DiIC18(3))	Reagent	Invitrogen	D282	To stain the probe track in the brain
Stainless Steel Machine Screw, Binding Head, Slotted Drive, #00-90, 1/8"	Material	Small Parts, Inc.	MX-0090-02B	Ground and reference screws
Magnet wire, 20G, nylon-polyurethane coating, MW80	Material	Small Parts, Inc.	B000IJYRP2	Ground and reference wire
Stainless Steel Machine Screw, Binding Head Slotted Drive, #000-120, 1/16"	Material	Small Parts, Inc.	MX-000120-01B	Anchor screws
N-3 All purpose Flux Liquid	Reagent	La-Co (Markal)	23512	Allows to solder stainless-steel
MicroGrid Precision Expanded Copper	Material	Dexmet	3 CU6-050 FA	Copper mesh for on-head Faraday cage
C&B-METABOND Quick! Cement System - Dentin Activator	Material	Parkell	S380
C&B-METABOND Quick! Cement System - Dental cement	Material	Parkell	S380
Sharp point tungsten needle and holder	Tool	Roboz Surgical Instruments Co.	RS-6064 and RS-6061	To make the hook to lift the dura
Carbide Bur HP 1/4	Tool	Henry Schein	9990013
Paraffin (Granules)	Material	Fisher Scientific	P31-500
Mineral Oil, Light (NF/FCC)	Material	Fisher Scientific	O121-1
GC ELECTRONICS 10-114 2-Part Epoxy Adhesive	Material	Newark Inc	00Z416
Type 1 LITZ 21 AWG 40/36 Red Single Polyurethane-Nylon (MW80-C) TO 0.041"+/-0.002" OD	Material	New England Biolabs	N28-36E-400-2	To make the cable between the headstage and the amplifier
32-channel Very Large Scale Integration headstage, 20x gain	Equipment	Plexon	HST/32V-G20	Headstage